1181505561 has 16 divisors (see below), whose sum is σ = 1647112320. Its totient is φ = 751921280.

The previous prime is 1181505553. The next prime is 1181505587. The reversal of 1181505561 is 1655051811.

It is a cyclic number.

It is not a de Polignac number, because 1181505561 - 2³ = 1181505553 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1181501561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 18301 + ... + 51941.

It is an arithmetic number, because the mean of its divisors is an integer number (102944520).

Almost surely, 2^1181505561 is an apocalyptic number.

It is an amenable number.

1181505561 is a deficient number, since it is larger than the sum of its proper divisors (465606759).

1181505561 is a wasteful number, since it uses less digits than its factorization.

1181505561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34176.

The product of its (nonzero) digits is 6000, while the sum is 33.

The square root of 1181505561 is about 34373.0353765855. The cubic root of 1181505561 is about 1057.1710377397.

The spelling of 1181505561 in words is "one billion, one hundred eighty-one million, five hundred five thousand, five hundred sixty-one".